Helicopter



May 20, 1947. R. R. HAYS 2,420,823

' HELICOPTER Filed Oct. 16, 1943 3 Sheets-Sheet 1 R. R. HAYS May 20, 1947.

5 Sheets-Sheet 2.

' May 20, 1947.

R. R. HAYS HELICOPTER Filed Oct. 16, 1945 3 LSheets-Sheet 3 Patented May 20, 1947 "UNITED STATES PATENT GFFICE HELICOPTER (Russell RhHays, Lawrence, .Kans.

' Application October 16, 1943 Serial No. 506,565

Claims. '1

' "This invention relates to helicopters andmore particularlyvto a dual control and torque compen-setting means for a helicopter during its difiercot-phases of flight.

The problems attendant to trahsitiomfrom hovering;v torrapid translational night helicopter'al machines using lifting-propellers'may be approached either a by initial-1y designing the machine for maximum efliciency duringtranslational flight; with adaptations made to permit hovering flight, or by designing first of all for emcienthovering flight and then adaptingto provide translationalfli'ght.

The-present invention utilizes the first stated approach: in incorporating "the basic principle of the tail plane as used in airplane" design being directly applicable to thehelicopter as. a:meansof torque compensation and control during translationahfli'ght, an early design therefor being disclosed in my priorPatent $377,124; with adaptation to achieve practicalhovering" flight. Ob-- viously, for such adaptation both" the counter torque means and the control of the-preferred translational-machine are no longer effective, yet thedesirability of utili'zing all or any ofithe structureessential to the translational machineif: possiblebecomes self-evident.

' The mostpromising structure capable for such adaptation appeared to bethat of the trailing portion of the fuselage, this in line withproposals previously madeto use airfoil-panels radially disposed in the propeller-s:slipstream as awcount'er torq-uedevice. Consequently if the partiot "the machine between theengine and the tail planes bebuilo in the form of an airfoil set at an'an'gle to the-propellers slipstream, a counter-torque forcemay be obtainedat little costin terms of structurev Such structure, however, was found to be not sufficient in itself to completelycounteract thetorque required to operate the propeller during hovering, nor does relative movement of it supplycompletencontrol moments. i Hence, ad'- di-tional: means of torque compensation and control are plainly called 'for.

Since the additional counter-torque device to be'useol is not essential to translational flight, it follows that minimum structure willzd'erive from the use o'f an auxiliary propeller or propellers the turning of'which can be discontinued after sufiicient translational speed has :been attained to makethe machines tail surfaces effective.

"Since" this auxiliary propeller should? furnish also a suitable: control means during" hovering flighaithe latter requirementsimplifies the choice 'of propellers, experience having shown that during hovering fi-ight a sectional feathering control ,1: revealed that the adaptation pmsents'severalsspecial problemsoi primary magnitude, not alone fromthe standpoint of control but also from the standpoint of" initial torque application.

'Mechanically; the transition from the i use. of a counter-torque propellertoa fixed-panel torquecompensatorwithtranslation is not a simple matter' of shifting gears as would be'the case: with a change inisp'eed in an 'autornobile. Rather, what is called-for is a means of decreasing, the-power inputtu the counter-torque propeller-inversely'to the force acting omthe panel compensator: with the'change from hoveringto'forward flight; and, a reversal of this process as forward'fiight: is decreased tohovering; Added towthis-initial complexity is the need for maintaining the lift of. the system substantially constant, which means that the relative speeds of-the main: promllerand the auxiliary propeller must beregulatedz with a similar degree ofnicety.

That the mechanical problems thus presented can. be dealt-with; successfully is in -la'rge part made po'ssiblefthrough theuse of a speed-reducti'on gearing incorporating: a differential between the hubs or: oppositely turnin co-axial propellers which equalizes their torque irrespective of their rotational speeds: in company with a: brake-suitable for stopping one of lthEIIJIOPGHBTS; disclosed in my co-pending application Serial No; 496,917, filedaJuly 31,1943; "Such a reduction-gearingbrake -.combination-logically provides for the starting and stopping of one propeller, but does-not however adequately'satisfy'the need for maintaining the liit'of the system constant. Consequently, means such as a clutch and change-speed-gear means are: incorporated between the engine: and the" rotor head assembly order that the ratio of the speed reduction means may be varied: in accordance: with therotational speed contemplatedmfrom the counter-torque propeller.

Accordingly, as appearsifromthe foregoing discussion, an object of thisi-nvention is broadly the provision of dual torquecompensating and, controlmeans for a helicopter comprising a counter rotating propellerv having a sectional controlior use during hovering flight, and vertical horizontal'ta'rl planes as a counter-torque and control means during translational flight.

Another: object as the provision of relatively simple mechanismz'by' which an auxiliary propeller co-axial with the main lifting propellermay be alternately started and stopped without greatly varying the lift on the system. and which provides a speed reduction of the engine which is greater with the auxiliary propeller stopped than when it is in operation.

A further object is the provision of a helicopter provided with counter-torque tail surfaces and having an auxiliary, co-axial lifting propeller in combination with the main lifting propeller, together with means by which the torque delivered to the auxiliary pro eller can be gradually transferred to the fuselage of the supporting structure as the counter-torque tail surfaces become increasingly effective with translation.

Yet another object is the provision of a helicopter having an auxiliary co-axial torque comnensating propeller mounted as described and having flaps on the trailing edges of its blades which are operated by a sectional control extending into the pilots cabin during hoverin flight, and having another set of conventional tail plane controls which are used during translational flight, at which time the auxiliary propeller is locked to the fuselage in a position providing least drag.

Still another object is the provision of an auxiliary co-axial propeller mounted for turning movement only about an axis common to a main lifting propeller which latter is mounted for free rocking movement about a horizontal axis as well as to rotate oppositely to the auxiliary propeller. as a result of which the latter gyroscopically resists tilting whereas the former does not.

Another object is the provision of an auxiliary torque compensatin propeller of the type described, mounted directly above the fuselage of the system and having one blade shorter than the other, which can be locked with the shorter blade in a forward position during translational flight so that the pilots visibility is accordingly increased.

Another object is the provision of an improved fuselage tail member having an airfoil crosssection and a control flap at its trailing edge, which is set at relatively high attack angles to the relative airstream passing over it, and having at its outer end a vertical panel also set at high attack angles to the relative airstream so that the two panels in combination form an airscoop the resultant force on which i opposed to the counter rotational tendency of a helicopter usin a single lifting propeller durin both hovering and translational flight.

Ancillary objects of the invention will be apparent from the following description thereof, taken with the accompanying drawings in which:

Fig. 1 is a View in side elevation of a helicopter utilizing a dual control and torque compensating means according to the invention.

Figs. 2 and 3 are plan and front elevational views, respectively, of the machine illustrated in Fig. 1.

Fig. 4 is an enlarged View in side elevation of the center section of such a machine showing the relative position of the machine, sub-pylon structure, rotor head assembly, and rotor.

Fig. 5 is a section taken generally along line 5-5 of Fig. 4 and showing the sectional control means by which the flaps of the lower rotor are varied in position.

Fig. 6 is a diagrammatic view in plan of a machine having dual torque means according to the invention, which illustrates the relative forces effective upon the anti-torque means during hovering flight; and

. the engine.

Fig. 7 is a diagrammatic view in plan illustrating the deflection of the lifting propellers slipstream through the use of torque compensating tail surfaces formed according to the invention to provide an air scoop.

Referring to the drawings, an engine In (Fig. 4) is mounted in a pylon structure ll provided with securing flanges I2 by means of which it is fixed to the fuselage 20. The upper end of the pylon l I comprises a bearing M for a rotor head assembly l5 aligned with the crankshaft i! of Arranged above the head is a rotor hub of the main lifting propeller i 8, the hub being mounted to provide relative rocking movement about axis BB of the blades l9 attached thereto. Disposed between the head and the bearing I4 is a lower auxiliary propeller or rotor 30, the blades 3! of which at their butt ends are fixedly secured to a radial flange 32 provided at the base of the conical head case 33, whereby the lower propeller turns with the case. The rotor head assembly l6 which is preferably of the type disclosed in my co-pending application Serial No. 496,917, filed July 31, 1943, incorporates a double set of planetary gearing carried in the lower end of the head case 33 and having a differential means intermediate them so that power applied to the sun gear of one set of planetaries by the crankshaft ll acts to reduce the engine speed and to turn the case 33 in opposite direction and with a torque equal to that applied to the hub of rotor I8 carried on a stub shaft mounted in the upper end of the head case and turning with the other set of planetaries.

The lower end of the head case 33 is fixed to an outer shaft 35 concentric with shaft I! and carried by the bearing It, the lower end of the shaft 35 being fitted with a friction brake 36, adapted to be operated by the hand crank 31. The sun gear of the other set of planetary gears is mounted on a shaft 40 concentric with shafts i! and 35 which extends to a freewheeling unit 4! which looks the sun gear of the set against rotation when a torque is applied by the driveshaft I! but turns to permit the rotors to autorotate in event of engine failure. As the drive and head assembly described corresponds to that of my prior application aforesaid, detailed illustration here is not believed to be necessary,

Carried directly beneath the free-wheeling unit 4| is a clutch and gear shift unit 5255 incorporated in the power transmission line, i. e., between crank shaft l1 and a coaxial shaft 50 driven thereby. This unit operates generally as does a similar unit in an automobile, with the exception that the unit gears serve only to increase the shaft speeds imparted to the head case 33 and are utilized for this purpose only when the auxiliary propeller 3E] turning with the head It has been released for rotation by means of the brake 35. As in an automobile, the unit clutch 52 is operated by a handle 54 extending to one side of the pilots seat 56 and the change-speed gears 53 are shifted by means of a handle 55 which extends out and above the pilots shoulder where it can be reached simultaneously by his other hand.

The blades 3| of the lower rotor 30 being fixedly secured to the flange 32 of the head assembly 16 as by bolts 65 comprise a rigid propeller. The blades thereof have trailing edge flaps 5 I, Fig. 5, mounted on aligned pivots havin the common axis EE which passes through the rotor center AA. A collar 62 disposed about the outer shaft 35 is provided with oppositely and symmetrically aeeo ee's extendingout and above' t-he pilots" head where it oan beeasi'ly re'ached.

J r It will :be evident i that, due to above described arrangement and mounting; movement of the control: handle him any dire'ction has the "efiect .of tilting the collar 62: in the opposite direction by comprising a universal joint symmetrical to'- the shaft axis A-J-uA. Thus ift-he handle I be pushed upward: alflap 6 l-islpushed downward attrailing phases of rotation land upward at forward phases of rotation,zthereby increasing-the attack angle of I the rear blade :and'decreasingthe attack angle of the forward blade to provide azforward pitching moment asis" well' known. in rthe art. The same actionapplieszto rolling moments. vDue to the precessional' moment of a propeller the pilot will. not: push the 1 handle" H directly toward 1 the direction of action ofi the-controltmomentildesired, but will anticipate this moment 'byfisome 60 in his rmovement 10f the 'control column =10.

Considering how theanti-torquer construction of fuselage; the tail end v2 l of the fuselage is built in the form of a thick section-vame on:airfoil which tapers slightly as: it extendsarearwardly- As shown in dotted li-nes (1 'ig; 3),i-the chord line of this airfoil -is set at an' angle 1X-to the plane of rotation--P--P of the maimprope'ller 18, with the leading-edge of the airfoil extending rotational when viewed from above. The angle Xandhen'ce the attack angle -of r the? tail. section zrnay; -Joe: as

great as 45 to the vertical, the mag-nitude'ro'fl this at-tack angle to the-slipstream of the lifting propeller 18 having been arrived at 'througl'ifree flight: testswof models: having a single radially. disposed counter torque "vane; of this general char-- acter; whichfirrdic'ated'that stabilitywofithe system was intimately"rassociated witlr thesusemf such high attack angles. It was moreover found that 'the use of a vertical tail surface shown in elevation and plan (Figs. 1 and 2) and set at an equally high attack. angle to the longitudinal axisofthe fuselage and extendingrupward. from the anti-torque vane 2| greatly enhanced its effectiveness.

While it would appear that the use' of an auxiliary counter-torque propeller would permit a decrease in the magnitude-ofthe angles desired on the tail surfaces, such wouldnot necessarily be the ease; it being apparent-that the'combin'ation of the high angularity and scoop-likevcharacterof the combined longitudinal and vertical airfoils provides attributes :not commonly: associated with the use of this tvpeofanti-toxiq-ire da vices. Thes attributes arise' by reasorr'ofxthe fact that airfoils set at a high angle and trans verse "to an 'airstream SS of circular'cross-sec- 1v 6 flnifiithe resultant-ainmovement is'in the direction N when' viewed' 'from above and hence is directly opposed to the rotational component of the slipstream" 'f lhat 'such transverse and counter rota-tional deflection of the slipstream should-cause thecenter of pressure' C' on the ceunter-torque airfoil 2| to move outwardly 'to' theposition Glogidallyiollows. Hence the effectiveness of thetail surfaces even during hoveringflight i increased through'incre'ase in the momentarm" K througli whicli the counter rotational force Lnow acts.

During' hovering r flight the; dominant direction of 'theslipstream- S-*S is downward. However, with a:-comparatively-small1 amount ,of transla- -tional travel thie -resultant airstream' 'I' acts to deflect thez slipstream rearwardly which 'serves to furthenshift the: airfoils centernf pressureC rearwardly as well astoiincrease the magnitude 'of the force L through the increased velocity of the *mean: airstream. With translatiom'ofany magnitude the force L consequently becomes suffioiellt 'to completely counter-act thetorque required toaturn the lifting' propeller' 18. -When the-force L becomes greater thanthe torque needed-to drive the lifting propeller 18; flaps 2B and. 23 (Figsi 1 and 2);:provided on the'vertical tail surface 25, and the' fuselage tail 2|; respectively, are operated in the same-fashion as a-conventional rudcler i to' prevent turning of #the machine. -iHorizontal stabilizers zit-having flaps 29, are also provided: at the encl of the ifuselage 'tail 2! the flaps being connected by cables (not shownywith a conventional control column or stick so that back and forth movement "of the 'sticlvsufiicesi to provide pitching moments' and aside .to: side movement rrollingmoments all in the direction-bf imovement of the stick as is well known in the art.

wlHaving .considered the operationiof therespec- .tive anti torque :me-ans and "associated": controls individually; consideration is now givento their interaction during. the transition iromz hovering to translationi flight. I Tobegin with; the engine having been started; but. the brake 3 6 s'et sothat the rotors arenotturhingythe brake-'isreleased, the :gear shift. lever 55: thrown to give a minimum speed reduction between the drive or crank 'shaft 1 T andlthe coaixial driven shaft: -50 extending to the rotorhead "assemblyl6, and the clutch 52 thrownfi'in L'to start bothrotors turning Since the "lower auizil-iary rotor- =30 is smaller than the maini rotor lfl it followsthat if unchecked it would build up: 'speed 'until the torque absorbed hyait- -equals-that; absorbedby the larger propeller'zlB.

.Howevenwith ereation of a'slipstream S-'S by the lifting propellers the fuselage panel'- -2i now becomes effective in creating aforce L o pposectdathe drag'of the main propeller l8. Cousequentlythe torque applied to the auxiliary propeller-no longen needs *to equal that applied tott'hamain propeller" in order" to balance 'the torque i forcescfiedtive upon the system. "Since any 'torque unbalance'in the system isindicated by a: tendencyot the fuselage" to rotate "about the propeller ax'is of rotation' A- -A-, it becomes comparatively simple 'for the pilot-to turn the brake iiai'idletluntilthe "friction-between the propeller 38: "the iuselage 2 0 is substantially" equal "to they force 1; times "the di-stance'-'K "as 'shown in Fl The" brake 36 i thus provides an easily variable means "of transmitting the torque applied to i the-lower i rotor tote the fuselage and torque balance of the system new results- Wherithe drag 7 of the main propeller D1 times the distance H fromthe propeller center AA to the blades center of percussion P, is equal to D2J plus LK.

Assuming that such torque balance is operative at the time the machine leaves the ground, the pilot now maintains control during hovering flight through use of the sectional control arm 79 and by use of a rudder bar operating the torque panel flaps 23, 26. Translation being desired, he pulls down on arm 19 to produce a forward pitching moment on the auxiliary propeller 39 thu causing the system to move forward as is well known in the art. Such movement makes the tail vanes 2| and more effective, hence further tightening of the brake 36 is required to prevent turning of the machine. This acts to speed up the main propeller is but chokes down the engine so that it now becomes necessary for the pilot to quickly throw the gears of the change-speed unit 53 to provide a greater speed reduction between the engine in and the rotor head assembly l6.

As further translational speed is attained the force L on the tail vanes suffices Wholly to equal D1I-I andsimultaneously the conventional stick control to the flaps 29 becomes operative in the usual manner. Consequently, the pilot now shifts gears again and proceeds to tighten the brake 36 until the auxiliary propeller 3| is locked against rotation. By proper manipulation of the brake, it is possible to lock the auxiliary propeller in a position in which it aligns with the direction of travel, and so' that its shorter end extends forwardly thereby to increase the pilots visibility.

The transition from translational to hovering flight is but .a reversal of this outlined procedure and hence no detailed description thereof appears to be necessary.

To simplify the movements required by the pilot of machines employing the dual control and torque compensating means of the present invention, an automatic gear shift may be substituted for the change speed-clutch unit 52-55. According to such advanced design as contemplated, the pilot will be required only to operate the brake and the sectional control levers in addition to the conventional control stick, and hence his manual operations for the precise control and advantages of torque compensation provided for all phases of flight are relatively limited.

As many changes could be made in carrying out the above construction-s without departing from the scope of the invention, it is intended that al1 matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. Counter-torque means for the lifting rotor of a helicopter, comprising in combination with a counter-torque panel mounted on the fuselage of said helicopter, a horizontally disposed counter-torque propeller mounted above said fuselage, and means including a brake for said propeller and variable speed transmission intermediate said propeller and said rotor for varying the rate of rotation of said propeller from zero rotation to a rotational speed absorbing a substantial portion of the driving torque of the engine of said helicopter during varying phases of flight.

2. Counter-torque means for the lifting rotor of a helicopter, comprising in combination with a vertically disposed counter-torque panel mounted on the fuselage of said helicopter, a horizontally disposed counter-torque lifting propeller mounted above said fuselage, and means including a brake for said propeller and variable speed transmission intermediate said propeller and said rotor for slowing the rate of rotation of said propeller during translational flight from a rotational speed absorbing a substantial portion of the driving torque of the engine of said helicopter to zero rotation and simultaneously increasing the rate of rotation of said rotor to a rotational speed absorbing all of the driving torque of said engine, whereby the speed of translational flight is increased.

3. Counter-torque means for the lifting rotor of a helicopter, comprising in combination with a counter-torque panel mounted on the fuselage of said helicopter, a horizontally disposed counter-torque lifting propeller mounted above said fuselage in co-axial relation to said lifting rotor, and means including a brake for said propeller and variable speed transmission intermediate said propeller and said rotor for starting and stopping said counter-torque propeller during varying phases of flight while maintaining the lift of said helicopter substantially constant.

4. Counter-torque means for the lifting rotor of a helicopter, including a contra-rotating lifting propeller mounted on a hub co-axially disposed below the hub of said rotor and above the fuselage of said helicopter, a brake for said propeller, variable speed transmission intermediate said propeller and said rotor, and different length blades for said propeller to render it directionally stable with respect to said hub when locked by i said brake with the shorter of said propeller blades extending into the direction of translation of said helicopter.

5. Control means for a helicopter, including the hub of a lifting propeller, propeller blades rigidly mounted upon said hub, trailing edge flaps artic-' ulatively mounted upon aligned hinge axes carried by opposite blades of said propeller, a universally mounted control member mounted on said hub in operative relation with said flaps and having one axis synonymous with said aligned hinge axes carried by said blades, and a control handle mounted on a slip ring carried by said control member whereby movement of said handle imposes a cyclic variation in the position of said flaps with respect to said blades to provide a sectional control for said propeller.

RUSSELL R. HAYS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

